In: Statistics and Probability
Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the
null hypothesis, and final conclusion that addresses both the claim and the significance level
alpha. Use the P-value method.
A sample of 17 jellybeans with a mean weight of 0.8295 g was taken. Assume that
σ is known to be 0.0565 g. Consider a hypothesis test that uses a 0.05 significance level
to test the claim that the mean weight of all jellybeans is equal to 0.8550 g (the weight
necessary so that bags of jellybeans have the weight printed on the package). Assume
the weight is normally distributed.
Solution:
This is a two tailed test.
The null and alternative hypothesis is,
Ho: 0.8550
Ha: 0.8550
The test statistics,
Z =( - )/ (/n)
= ( 0.8295 - 0.8550 ) / ( 0.0565 / 17 )
= -1.86
P-value =2* P(Z < z )
= 2 * P(Z < -1.86 )
= 2 * 0.0314
= 0.0628
The p-value is p = 0.0628, and since p = 0.0628 > 0.05, it is concluded that the null hypothesis is fail to rejected.
There is not enough evidence to test the claim that the mean weight of all jellybeans is equal to 0.8550 g